For architectures of conventional underwater pumping stations, it was for a long time customary to use pumps that are not very powerful (<1 MW) and that have a relatively low pressure differential (i.e. low ΔP, <50 bar).
With the advances in technical progress, more powerful pumps must be used (about 2.5 MW), for example in so called recent “Offshore deep-sea drilling” projects such as the Pazflor project and the GirRI project. These pumps can be suitable for generating a pressure differential ΔP of about 130 bar.
These new pumps can in particular be:                pumps referred to as “MPP” (for “multiphase pump”) with a substantial increase (or “High Boost”);        hybrid pumps.        
Although the power of these pumps was increased, the pumping devices that accompany these pumps have not changed (i.e. pumping stations outside the pumps).
However, such devices are not free of defects.
Indeed, although these pumping devices satisfied the characteristics of low-power pumps, the operating constraints of high-power pumps impose improving these devices.
This invention improves the situation.
This invention proposes a multiphase pumping block device comprising:                a pump suitable for pumping a pumping fluid;        a bypass circuit suitable for enabling the flow of a fluid from an area upstream of the pump to an area downstream of the pump by bypassing the pump, with the bypass circuit comprising at least one non-return valve suitable for blocking the flow of the fluid from the area downstream of the pump to the area upstream of the pump.        
The pumping block device is suitable for being connected to a set of pumping circuits, with said set of circuits comprising a main bypass circuit suitable for enabling the flow of a fluid from an area upstream of the connected pumping block to an area downstream of the connected pumping block by bypassing said connected pumping block.
The pumping block device is arranged in order to be disconnected from said set of circuits for maintenance.
The term “area downstream of the pump” refers to an area connected to the outlet of the pump.
The term “area upstream of the pump” refers to an area connected to the inlet of the pump.
The upstream area (respectively the downstream area) of the pump can be advantageously close to the inlet (respectively the outlet) of the pump and are inside the pumping block. Indeed, the bypass circuit makes it possible to create a diversion within the pumping block itself, this pumping block is suitable for being retrieved easily with respect to the rest of the pumping station. This retrieval can make it possible in particular to replace certain defective parts of the pumping block (such as valves, impellers, etc. or any other parts subjected to high constraints or stresses).
The non-return valve located on the bypass circuit can make it possible to limit the recirculation of pumped fluid when the pump is actuated and operational, and when the pressure differential between the inlet and the outlet of the pump is positive.
The set formed by the set of pumping circuits and the pumping block device can be called a “pumping station”.
In the case of starting of the pump, this bypass circuit can make it possible to prevent allowing the free flow to flow through the pump and as such prevent any abnormal wear and tear of the latter (ex. mechanical seals).
Using this bypass circuit integrated into the pumping block, the starting of the pump can be carried out without using the main bypass circuit conventionally used for this purpose.
In an embodiment, the pumping block device can further comprise an anti-retour suitable for blocking the flow of a fluid from the area downstream of the pump to the pump.
As such, the non-return valve can protect the pump from any backflow or abnormal flow of fluid and which could result in a degradation of the pump.
In addition, the bypass circuit further comprises a valve suitable for controlling the flow of a fluid in the bypass circuit. This valve can be a valve of the “choke valve” or “on-off valve” type.
In case of stoppage of the pump, it can be useful to open this valve in order to balance the upstream and downstream pressures of the pump. This opening can makes it possible to prevent using the main bypass circuit and as such limiter the wear and tear of its various parts such as its valves.
Other characteristics and advantages of the invention shall further appear when reading the following. The latter is purely for the purposes of information and must be read with regards to the annexed drawings wherein: